[libc][NFC] add remarks to the setjmp implementation #137066
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Contributor
There was a problem hiding this comment.
Pull Request Overview
This pull request adds clarifying remarks to the x86_64 setjmp implementation, explaining the use of naked functions and linking to a related LLVM issue.
- Added detailed comments explaining the rationale for using naked functions.
- Provided a reference to the LLVM issue for additional context.
Member
|
@llvm/pr-subscribers-libc Author: Schrodinger ZHU Yifan (SchrodingerZhu) ChangesWe use naked functions to avoid compiler-generated prologue and epilogue. Despite GCC document list this as an supported case for extended asm, the generated code is not wrong as we only pass in constant operands to extended asm. See #137055 for related remarks. Full diff: https://github.com/llvm/llvm-project/pull/137066.diff 1 Files Affected:
diff --git a/libc/src/setjmp/x86_64/setjmp.cpp b/libc/src/setjmp/x86_64/setjmp.cpp
index 28e52712c785d..83d0b635ffcbf 100644
--- a/libc/src/setjmp/x86_64/setjmp.cpp
+++ b/libc/src/setjmp/x86_64/setjmp.cpp
@@ -6,6 +6,12 @@
//
//===----------------------------------------------------------------------===//
+// We use naked functions to avoid compiler-generated prologue and epilogue.
+// Despite GCC document list this as an supported case for extended asm, the
+// generated code is not wrong as we only pass in constant operands to
+// extended asm.
+// See https://github.com/llvm/llvm-project/issues/137055 for related remarks.
+
#include "hdr/offsetof_macros.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
|
Co-authored-by: Copilot <[email protected]>
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
SchrodingerZhu
changed the title
Contributor
Author
|
Merge directly as the change is trivial |
Contributor
|
LGTM. |
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
We use naked functions to avoid compiler-generated prologue and epilogue. Despite GCC documentation listing this as an unsupported case for extended asm, the generated code is not wrong as we only pass in constant operands to extended asm. See llvm#137055 for related remarks. --------- Co-authored-by: Copilot <[email protected]>
GeorgeARM
pushed a commit
to GeorgeARM/llvm-project
that referenced
this pull request
May 7, 2025
We use naked functions to avoid compiler-generated prologue and epilogue. Despite GCC documentation listing this as an unsupported case for extended asm, the generated code is not wrong as we only pass in constant operands to extended asm. See llvm#137055 for related remarks. --------- Co-authored-by: Copilot <[email protected]>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
We use naked functions to avoid compiler-generated prologue and epilogue.
Despite GCC documentation listing this as an unsupported case for extended asm, the generated code is not wrong as we only pass in constant operands to extended asm.
See #137055 for related remarks.